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  • ihatemornings's Avatar
    01-27-2021, 02:13 PM
    Easy as that, eh? Hats off to you, sir. :) Iíll go with a decent 9V PSU for now and iron out the finer audio details then see how much more energy I have for power supply design. Thanks everyone for the help! Iíve...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-27-2021, 01:14 PM
    Swapping the power supply for a better one (a Korg 9V PSU instead of a random cheapo) eliminates almost all of the noise. Gah. If I wanted to make the circuit more resilient to cheapo power supplies by adding some...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-27-2021, 12:29 PM
    @fdaniels good question! I had tried that a while back, but not recently. Running the circuit from a 9V does indeed eliminate the noise. So... I need to filter the power supply?
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-27-2021, 10:25 AM
    I came across this post that sounds like a very similar problem to mine, and it made me wonder whether my skimpy breadboard cables were not giving me a clear enough ground connection. I swapped all the ground wires out...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-26-2021, 11:04 AM
    The JFET buffer is quite common in guitar pedals (this sort of thing), but a TL07x buffer makes sense too (and should be better quality). Iíve swapped the buffers out for TL071s Ė they work fine but the noise is still...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-24-2021, 07:27 PM
    @fdaniels thanks for the pointer on the inductor position Ė I think I misunderstood your earlier recommendation. This makes much more sense. Hereís the full circuit that Iím tinkering with. One of the Teensy outputs...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-24-2021, 12:27 AM
    Quick experiment Ė I donít think this is the correct approach, but it does eliminate the noise and maybe that would be helpful in diagnosing the problem. I grounded the mixer to the Teensy audio boardís line out...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-23-2021, 11:52 PM
    Iíve made some progress! A few steps forward, a few steps back. I bought some 33uH inductors and added them to the circuit as @fdaniels suggested. They reduced the power supply whine a little. Then I did a lot of...
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-18-2021, 04:34 PM
    @jonr @fdaniels @MarkT @Blackaddr thanks for the tips! That all makes a lot of sense. Iíll make some tweaks to the circuit and see how I get on.
    26 replies | 1175 view(s)
  • ihatemornings's Avatar
    01-17-2021, 11:12 PM
    Iíve been working on a Teensy 4.0-based music machine for a while, and Iím getting down to the last niggly noise issues. Iím hoping this is something people have solved before, but I havenít managed to find any...
    26 replies | 1175 view(s)
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How to reduce power supply noise 01-27-2021 02:13 PM
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